1. Field of the Invention
The present invention relates to the removal of an unpleasant odor generated by use of a permanent waving agent containing a mercapto compound.
2. Description of the Prior Art
For a hair setting operation based on the permanent waving technique, hitherto, there have been widely carried out a method comprising reduction-breaking the disulfide bonds between the keratin molecules of hair by a reducing agent (usually called a primary agent such as thioglycolic acid and cysteine, and then oxidizing the broken parts by an oxidizing agent (usually called a secondary agent) such as bromate, perborate and hydrogen perxoride to form the disulfide bonds again.
When such a reducing agent as mentioned above, containing a mercapto compound, is used, however, it produces hydrogen sulfide having an unpleasant odor, with a defect giving an unpleasant feeling to these surroundings.
To cope with this problem, in general, a masking technique has been utilized whereby only the odor of a permanent waving agent can be weakened to some degree. But, it was next to impossible for the masking technique to inhibit the hydrogen sulfide odor generated through the reaction of a permanent waving agent with hair, this is an unpleasant odor.
To the purpose of obviating these defects, there have hitherto been proposed various kinds of counter-measures.
In British Pat. No. 674195, for example, a method for removing hydrogen sulfide produced by carrying out a permanent waving operation is disclosed, which comprises adding a tetrammine salt of zinc, copper, nickel or cobalt into a permanent waving agent consisting mainly of a thioglycollate.
This method is however not preferable, because these tetrammine salts, except for the zinc salt, form a colored chelate together with thioglycolic acid or the like and further oxidize thioglycolic acid.
In addition, the zinc salt must be used in a considerable amount to remove the unpleasant odor and has a defect of lowering the wave-forming power, this is an object of a parmanent waving agent, because it forms a strong complex together with thioglycolic acid.
Furthermore, there have been proposed various means, by way of example, as disclosed in Japanese Patent Publication No. 37013/1972, using an unsaturated carboxylic acid, Japanese Patent Publication No. 48740/1974 using honey and Japanese Patent Laid-Open No. 154116/1982 using a porous material and an air-tight cap, but it can not expect any satisfactory effect from all of these means.